The present day packaging of products such as raisins, detergents, cereals and the like in cartons employs sophisticated, high speed machinery. This machinery is quite efficient, but the problem of carton "racking" during filling and sealing causes frequent troubles. The cartons used in these operation have a top closure of rectangular configuration; that is, when viewed from above, the top closure forms a perfect rectangle. However, frequently the high speed handling causes the cartons to rack and this rectangular configuration is distorted causing sealing problems and unsightly appearance. A second problem arises when the outer major flap is folded over and sealed to the underlying flaps by glue, preapplied adhesive, hot melt or other means. Due to the high speed operations, pressure can be applied to the folded outer major flap for only a very short time. Conventional inner flaps have little inherent rigidity and will bend inwardly when pressure is applied to prevent a tight seal of the closure. Interacting cut areas at the side edges of the inner flaps will correct racking which may have occurred during handling and filling and will prevent further racking during folding and sealing, while the intermeshing of these same inner flaps will provide rigidity during sealing to give better, tighter seals.